Quality Of Fish Meat Research Articles

Influence of Aquaculture Environments on the Muscle Quality of Golden Pompano (Trachinotus ovatus) in the Beibu Gulf: A Multifaceted Analysis of Nutritional, Textural, and Flavor Profiles

Golden Pompano (Trachinotus ovatus) is a primary source of high-quality protein, yet its muscle quality is significantly influenced by varying aquaculture environments, impacting both nutritional value and marketability. This study aimed to assess the muscle quality of T. ovatus across estuary, nearshore, and offshore aquaculture environments in the Beibu Gulf. We employed standardized protocols to evaluate key quality parameters including basic nutritional components, amino acids, fatty acids, volatile substances, flavor nucleotides, and thermal stability through heat analysis. Data analysis was conducted using statistical comparisons across different environments to identify significant differences. Our results indicated that offshore aquaculture environments yielded T. ovatus with superior nutritional profiles, exhibiting higher moisture, ash, crude protein, and crude fat contents. Additionally, offshore-cultivated fish demonstrated better textural qualities and higher levels of essential amino acids, unsaturated fatty acids, and umami-flavor nucleotides. These findings highlight that offshore aquaculture environments optimize the muscle quality of T. ovatus, suggesting implications for environmental management and enhancing fish meat quality in aquaculture practices.

Optimal balance of organic detritus and feed for fish growth and water quality improvement through regulating nutrients cycling

In order to explore the effects of different feed composition on the nutrient level and microbial loop structure in aquaculture ponds, a field simulation experiment in aquaculture ponds was conducted by adding different proportions (0%, 20%, 40% and 60%) of bagasse to fish feed for combined feeding. The addition of bagasse significantly reduced the levels of various forms of nitrogen and phosphorus in the water, especially with the addition of 60% bagasse. In the treatments without addition and with 20% bagasse added, nitrogen and phosphorus levels remained relatively high, which should be attributed to the decomposition of feed and the release of sediment, ultimately stimulating the abundant reproduction of algae. Bacterial growth was limited due to insufficient supply of organic carbon, and the growth of fish relied more on the components of the feed. With the addition of 60% bagasse, the high organic carbon and low nitrogen and phosphorus levels could not support the growth of phytoplankton, bacteria, and zooplankton. It is inferred that organic carbon may be more degraded into carbon dioxide, ultimately limiting the growth of fish. Adding 40% bagasse achieved a balanced level of carbon, nitrogen, and phosphorus, establishing a healthy and stable microbial loop structure (including phytoplankton, bacteria, and zooplankton). Most nutrients were converted into plankton, which then became natural food for fish, ensuring complete nutrient utilization. This is beneficial for both water quality improvement and fish reproduction. Therefore, adding a moderate proportion of bagasse to the feed can maximize the effects of water quality improvement, fish reproduction, and even the quality of fish meat.

Effects of Chemically and Green Synthesized Zinc Oxide Nanoparticles on Shelf Life and Sensory Quality of Minced Fish (Pangasius hypophthalmus).

The purpose of this study was to investigate the effect of chemically and green synthesized zinc oxide nanoparticles (ZnO-NPs) on the shelf life and sensory quality of fish meat. In this study, ZnO-NPs were synthesized by employing the colloidal chemistry (CZnO-NPs) and green synthesis (GZnO-NPs) methods, and they were also characterized to assess their morphology. The synthesized ZnO-NPs, ZnO, and zinc acetate (ZnA) were used for the preservation and fortification of fish (Pangasius hypophthalmus) meat at 20 mg/kg of Zn. In a six-day storage study at 4 °C, the fish samples were evaluated for their sensory attributes (color and odor), physicochemical quality (pH and total volatile base nitrogen), oxidative changes (thiobarbituric acid-reactive substances and peroxide value), and microbial loads at 0, 3, and 6 days of storage. The fortification of raw fish with the synthesized CZnO-NPs produced better sensory attributes (color and odor) and maintained a pH non-conducive to microbial growth throughout the entire storage period compared with the control, ZnO, and ZnA-fortified samples. The GZnO-NPs largely did not provide any added advantage over CZnO-NPs but sometimes responded better than the control, ZnO, and ZnA samples. Oxidative status and total volatile base nitrogen were lower for CZnO-NPs in refrigerated fish compared with the other treatments. The ZnO-NP-fortified fish had the lowest counts of total viable bacteria, coliforms, Staphylococcus spp., and Vibrio spp. Hence, the fortification of fish with synthesized CZnO-NPs is promising as a food additive to reduce microbial spoilage and lipid peroxidation of fish in storage.

Hydroxyl Radical-Induced Oxidation on the Properties of Cathepsin H and Its Influence in Myofibrillar Proteins Degradation of Coregonus peled In Vitro.

The most frequently occurring protein modification in fish postmortem is oxidization, which further affects meat quality through multiple biochemical pathways. To investigate how hydroxyl radicals affect the structure of cathepsin H and its ability to break down myofibrillar proteins in Coregonus peled, cathepsin H was oxidized with 0, 0.1, 0.5, 1, 5, and 10 mM H2O2 and subsequently incubated with isolated myofibrillar proteins. The results showed that as the H2O2 concentration increased, the carbonyl and sulfhydryl contents of cathepsin H significantly increased and decreased, respectively. There were noticeable changes in the α-helix structures and a gradual reduction in UV absorbance and fluorescence intensity, indicating that oxidation can induce the cross-linking and aggregation of cathepsin H. These structural changes further reduced the activity of cathepsin H, reaching its lowest at 10 mM H2O2, which was 53.63% of the activity at 0 mM H2O2. Moreover, desmin and troponin-T all degraded at faster rates when cathepsin H and myofibrillar proteins were oxidized concurrently as opposed to when cathepsin H was oxidized alone. These findings provide vital insights into the interaction mechanism between oxidation, cathepsin H, as well as myofibrillar protein degradation, laying a groundwork for understanding the molecular mechanisms underlying changes in fish meat quality after slaughter and during processing.

Sterilization of fish through adaptable gRNAs targeting dnd1 using CRISPR-Cas13d system

Sterilizing fish is a valuable technique not only for preventing genetic contamination from escaped aquaculture fish but also for enhancing fish meat quality. The clustered regularly interspaced short palindromic repeats-CRISPR-associated 13d (CRISPR-Cas13d) system is capable of RNA-targeted gene knockdown with reduced off-target effects. Unlike morpholino knockdown, which is limited to specific target sites, the CRISPR-Cas13d system utilizes the entire mRNA as a target site for gRNA. This enables the design of adaptable gRNAs by targeting the conserved sequences across fish species, leading to promising sterilization for a wide variety of aquaculture fish. In this study, we demonstrated that the effectiveness of this system in fish sterilization by the knockdown of dead end1 (dnd1) and nanos3, which are crucial for germ cell development. Initially, we demonstrated that gRNAs designed using the cas13design tool, which was developed based on studies of cultured mammalian cells, effectively induced germ cell-deficient medaka with low-cytotoxicity. Additionally, we identified the nucleotide positions of the gRNA (seed sequence) that are crucial for knockdown in teleost fish. These data will be valuable for designing adaptable gRNA in teleost fish and targeting multiple paralogous genes. To develop an adaptable sterilization technique using the CRISPR-Cas13d system, we aligned 81 dnd1 sequences from 70 fish species and identified a highly conserved region of the gRNA targets. Despite not finding a perfectly matched target region in the dnd1 alignment, we designed 15 adaptable gRNAs that potentially targeting dnd1 in 55 out of 70 fish species, leveraging sequences from representative aquaculture and aquarium fish (salmon, tilapia, puffer fish, amberjack, tuna, guppy and carp) and experimental model fish (medaka, zebrafish, and stickleback. To confirm whether adaptable gRNAs had a knockdown effect, we initially injected the gRNAs into medaka embryos. Adaptable gRNAs with a single-nucleotide mismatch against medaka dnd1 resulted in the complete loss of germ cells with little cytotoxicity, suggesting that mismatches are unlikely to induce off-target effects crucial for embryonic development. Additionally, adaptable gRNAs designed based on the salmon dnd1 sequence, which was 100% identical in the Oncorhynchus, Salvelinus, and Salmo groups, effectively generated germ cell-deficient rainbow trout. These results indicate that the knockdown of dnd1 using the CRISPR-Cas13d system is effective for sterilizing both aquaculture and experimental model fish species. Moreover, the adaptable gRNAs designed in this study can potentially sterilize a diverse range of fish species.

A solution for fillet quality: Slaughter age's effect on protein mechanism and oxidation

Physico-chemical properties of fish flesh are reliable predictors of fillet quality and nutritional value. In our study, the age-related variations of the chemical composition, pH, water activity (aw), water holding capacity (WHC), color and texture analysis, protein thermal stability, myofibrillar fragmentation index (MFI), glycogen content, protein oxidation and protein profiles were investigated in Oncorhynchus mykiss (rainbow trout) fillet. The results revealed that protein denaturation temperatures (Tmax1 and Tmax2) decreased by 2 % and 11.6 % depending on fish age. Tmax1 and Tmax2 values in the same groups were raised 71 % at 11 months' fish and this increase was 58 % at 23 months’ fish. An age-related reduction by 66.6 % and 31.25 % was noticed for protein oxidation markers sulfhydryl groups and disulfide bonds. MFI value increased by 86.6 % connected with age.The characteristics of fish meat quality are complex and are influenced by various factors that affect the degree of freshness of the product and its acceptance in the market. Taking into account the different demands of the consumer, this study has shown that age at slaughter has an impact on final product quality and that the recommended age at slaughter, taking into account market weight, positively affects meat quality.

Active packaging coating based on agarose grafted with benzoic acid derivatives: Preparation, characterization and application in fish preservation

Agarose based on gel strength can not meet the needs of diverse applications, and the structural modification of agarose is helpful to improve its functional properties and promote the economic benefits of the agarose industry chain. This study focuses on making agarose as an active packaging material with specific functions. Agarose was modified with p-hydroxybenzoic acid (Ph) and 3, 4-dihydroxybenzoic acid (Da) to produce agarose derivatives with grafting rates of 4% and 12% (Ph-Ag@4%, Ph-Ag@12%, Da-Ag@4%, and Da-Ag@12%). Characterization techniques confirmed the successful introduction of Ph and Da onto agarose, with grafting occurring at the C-6 position in d-galactose. Both Ph-Ag and Da-Ag exhibited significantly enhanced antioxidant and antibacterial properties. Da-Ag@12% showed remarkable improvements in DPPH and ABTS radical scavenging activities from 0% to 66.01% and 2.49%–84.73%, respectively. Ph-Ag@12% exhibited inhibition rates of 100% against Escherichia coli and Staphylococcus aureus. After modification, Ph-Ag and Da-Ag maintained good gelling and film-forming properties. Fish preservation experiments revealed both Ph-Ag and Da-Ag coatings effectively suppressed microbial growth, slowed down lipid oxidation, minimized water loss, and maintained the texture and appearance of fish meat. These coatings improved fish meat quality and extended its shelf life, with Da-Ag@12% showing the most promising results.

The effect of high-pressure processing on quality of seafood meat- a review

High-pressure (HP) technology is useful for preserving food. When it applied to fish and shellfish, high-pressure (HP) treatment could result in several kinds of benefits since it would affect the extension of the shelf life of this extremely perishable seafood product. In contrast, under extreme conditions, changes in the meat's appearance, texture, and chemical composition can be observed in fish. The most significant modifications took place between 200 and 300 MPa, causing proteins to either partially or completely denature. These changes in turn affected the pH, hardness, whitening, water-holding capacity, the beginning of lipid and protein oxidation, and an increase in hardness. The brief overview of HP technology and its main impact on fish meat quality were reviewed in this paper by considering the targeted constituents and underlying mechanisms.

MICROBIOLOGICAL QUALITY OF SOUS VIDE FISH MEAT TREATED WITH HONEY

The research was aimed at studying the influence of sous vide heat treatment on the microbiological quality of fish meat marinated in honey sauce. The samples were vacuum packed and cooked at 55°C, 60°C, 65°C and 70°C for 15 minutes. The samples were first stored for 24 hours at 4°C and then stored for 7 days at 4°C. The microbiological quality of fish meat in honey sauce were examined. Microbiological indicators such as the total viable count (TVC), the number of coliform bacteria (CB) and the lactic acid bacteria (LAB) were determined. The microbiota was identified by mass spectrometry using a MALDI-TOF MS Biotyper (Bruker Daltonics, Germany). Microbial counts varied significantly depending on temperature and storage in honey sauce. TVC in raw fish meat was 2.89 log CFU.g-1 stored at 4°C. TVC in raw fish meat was 4.56 log CFU.g-1 after 7 days of storage at 4°C. TVC in sous vide fish meat samples without honey ranged from 1.62 to 3.02 log CFU.g-1. TVC in sous vide fish meat samples with honey sauce was < 1 log CFU.g-1. The presence of coliform bacteria was not detected in the samples. LAB in raw fish meat was 2.47 log CFU.g-1 in the sample stored at 4°C. LAB in raw fish meat was 2.77 log CFU.g-1 after 7 days of storage at 4°C. LAB in sous vide fish meat samples without honey ranged from < 1 to 1.33 log CFU.g-1. LAB in sous vide fish meat samples with honey sauce ranged from < 1 to 2.66 log CFU.g-1. Our results show, that in the samples that were stored in honey sauce, the number of microorganisms decreased and even no microorganisms were detected.

Monitoring of individual indicators of safety and quality of water and fish of Khadzhibey estuary

Water significantly influences the quality and safety of fish because it is the environment for the life and cultivation of fish. A study of hydrochemical and microbiological indicators of the water of Khadzhibey estuary was conducted; the content of heavy metals in it was determined. In the Khadzhibey estuary, from 2022 to 2023, the water acidity indicator was stable, did not exceed the established hygienic standards for fish farms, and was within the range of 7.6 ± 0.4–8.4 ± 0.3 mg/L, which completely meets the requirements for fish farming. The maximum salinity in the estuary is observed in summer and is 15 % higher compared to winter and spring indicators. The water type of the estuary is mixed with moderate mineralization. It was established that the zinc content in water samples from the estuary exceeds the maximum permissible concentration by 2.6 %. The content of Cadmium, Lead, Copper, and Mercury is constant and does not exceed the maximum allowable concentration for fish farms. An increase in zinc content in water is a stress factor and affects the quality of fish meat. The research results showed that the content of mesophilic aerobic and facultative anaerobic organisms does not exceed the maximum permissible level in muscle tissue cultures of common carp and round bull caught by commercial fishing from the Khadzhibey estuary. Escherichia coli bacteria, Staphylococcus aureus, Listeria monocytogenes, and pathogenic microorganisms were not detected in the samples of the fish subject to the study. According to the microbiological indicators of water and fish, common carp and Round goby caught by industrial fishing in the Khadzhibey estuary are safe and allowed for further consumption by humans and animals.

The influence of Opisthorchis felineus infection on the nutritional quality of fish meat and an assessment of fish processing methods

The influence of Opisthorchis felineus infection on the nutritional quality of fish meat and an assessment of fish processing methods

Body Composition and Fatty Acid Profile of Carps under the Influence of Ammonium Nitrate and Feed Supplementation

Aquaculture plays a significant role in the food requirements of an increasing population. Fertilization, composition of diet and its feeding rates affect the fish meat quality. Objectives: To observe the body composition and fatty acid profile of carps towards rice polish and maize gluten supplementation in ammonium nitrate fertilized ponds. Methods: Two earthen ponds containing total 55 fishes were selected with each pond stocked with Rohu (Labeo rohita), Silver carp (Hypophthalmichthys molitrix) and Mori (Cirrhinus mrigala) at the final ratio of 2:1:1 respectively. Ammonium nitrate and rice polish was the feed in pond 1 while ammonium nitrate and maize gluten were the feed in pond 2. Results: Proximate analysis of fish meat samples showed that Labeo rohita showed maximum moisture contents in P1 (78.51%) and minimum in P2 (77.27%) in Hypophthalmichthys molitrix. Maximum crude protein was recorded as (17.93%) in L. rohita, under P2 whereas minimum crude protein was observed in P1 (16.81%) in L. rohita. C. mrigala remained well-known with minimum fat contents (1.71%) in P2 but maximum (1.96) in Labeo rohita in P2. H. molitrix gave the major ash contents of (1.85%) in P1 as compared to other experimental fish species. Highest position of carbohydrate contents in P1 was occupied by H. molitrix. The most abundant fatty acids recovered were monounsaturated fatty acids (37%) followed by polyunsaturated fatty acids (33%) and saturated fatty acids (29%). Conclusions: The body composition and fatty acid profile of carps varies depending upon their diet and feeding rate.

Investigation of quality parameters of common carp (Cyprinus carpio) meat marinated with traditional method used in Anatolia during storage at −18 °C

Improving the sensory quality of fish meat is crucial aspect to enhance fish consumption. In this study, the cooking methods in some Anatolian cities where common carp is consumed very popularly were investigated, and carp meat was marinated using different ratios of lemon juice (0.00%, 40.00%, 50.00%, and 60.00%) and salt (10.00%) using the traditional method. After marinating, the effects on the sensory, chemical, and microbiological quality of carp fillets stored at −18 °C were investigated. As a result of the research, it was observed that lemon had positive effects on the shelf life of fish meat. Peroxide value (PV), pH value, Thiobarbituric Acid (TBARS), the total number of psychrophilic bacteria, and the total number of yeast and molds were lower in the groups marinated with lemon juice and salt compared to the control group. In addition, it was observed that the panelists liked the carp meat of the groups marinated with lemon juice.

Microstructural analysis of frozen and salted fish and seafood meat

To evaluate the quality and safety of fish and seafood meat, along with generally accepted methods, new histological research methods are used, which allow establishing microscopic changes in fresh, spoiled, and canned foods. The purpose of this study is to examine the microscopic structure of salted fish meat (Herring, Pollock) and seafood (squid, mussels) by freezing. It was confirmed that fish meat is composed of skeletal muscle, fibrous connective (endo- , perimysium) tissues with blood, lymphatic vessels, and nerves. Muscle tissue fibres have the appearance of cylindrical formations, with well-defined transverse striation and numerous nuclei. The basis of seafood meat is smooth muscle tissue with layers of loose fibrous connective tissue, blood vessels, and nerve fibres. Smooth muscle cells are fusiform in shape, without transverse striation and with a single nucleus. During freezing of fish meat at a temperature of -18ºС, ice crystals are small and well-defined in the endo- and perimysium, and at a temperature of -23ºС – in muscle fibres. When fish is re-frozen, large ice crystals form in both the muscle fibres and the endomysium and perimysium of the muscles, the muscle fibres are fragmented and have cracks. In frozen seafood meat, there is a deformation of bundles of smooth muscle cells and their fragmentation. During the salting of fish meat, in the dehydration phase, a decrease in the diameter of muscle fibres and the width of the endo- and perimysium is noted, the transverse striation and nuclei of muscle fibres are well expressed, and in the dehydration phase, the reverse processes occur. Meanwhile, the fibres become straight with cracks and crevices, and graininess is noticeable in the endomysium and perimysium. Based on the results obtained, it is possible to evaluate the microstructure of frozen and salted fish and seafood meat, which is important when monitoring the suitability of food products for consumers

Insight into the protein oxidation impact on the surface properties of myofibrillar proteins from bighead carp

The objective of this study was to elucidate the influence of oxidative modifications of myofibrillar proteins (MPs) on their surface properties. Oxidative modifications (deamination, formation of disulfide bonds and Schiff bases), particle size, net surface charge, and binding ability of volatiles (2-enthylfuran, 1-octen-3-ol, hexanal, and octanal) of oxidized MPs was measured. Molecular docking of volatiles with actomyosin was performed using Qvina-W program and the specific oxidative modifications (monoxidation and deamination) of MPs were determined using LC-MS/MS. Results showed that oxidation of Cys (forming sulfinic, sulfonic, sulfenic acid, and disulfide bonds), monoxidation of Ala, Lys, Glu, and Asn, and deamination of Lys changed the surface properties of oxidized MPs including enhanced surface hydrophobicity and decreased affinity to volatile compounds and water. Overall, this study gives evidence of how protein oxidation affects the properties of MPs and therefore deteriorates fish meat quality.

Effect of nutritionally complete feed with different fatty acid profile on the fatty acid composition of common carp fillet

AbstractHungarian pond fish production is based on grains, but in the last few years, new ideas and efforts have appeared to intensify carp production technology. The basic objective was to change grain-based feeding to nutritionally complete feeds, which ensure rapid growth and more efficient feed conversion rates. This study aimed to utilise empty ponds during the summer period for carp production. Thus, there is no need for fish producers to catch fish in large ponds at the operating water level to satisfy smaller market demands appearing during the summer.The other aim was to compare the meat quality of fish raised on traditional and nutritionally complete feed until market size in the last year of production. Fatty acid profile and the levels of saturated, monounsaturated, and polyunsaturated fatty acids in fish fillets were specified, and their ratios were analysed. The result showed that nutritionally complete feed with different fatty acid composition affects the fatty acid composition of carp fillet during the rearing period. Quality of the fillet of carp fed with higher unsaturated fatty acid content became more favourable to the consumers due to health promoting effect of polyunsaturated fatty acids.

Cross-linking effects of EGCG on myofibrillar protein from common carp (Cyprinus carpio) and the action mechanism.

The cross-linking effects and action mechanism of epigallocatechin gallate (EGCG) on myofibrillar protein from common carp (Cyprinus carpio) were investigated. According to particle size, zeta potential, and atomic force microscopy, EGCG could cause the aggregation of myofibrillar protein, while hydrogen bonds and electrostatic interactions were the main molecular forces. With the measurement of Fourier transform infrared spectrum, surface hydrophobicity, fluorescence spectrum, circular dichroism spectrum, and molecular dynamics simulation, EGCG could make the spatial configuration of myofibrillar protein loose, enhance the exposure of amino acid residues, and further change its secondary and tertiary structures by forming intermolecular and intramolecular hydrogen bonds with myofibrillar protein. In addition, the gel properties of myofibrillar protein were improved by EGCG. All results suggested that EGCG had the cross-linking effects on myofibrillar protein in carp meat and could further improve its properties, which showed the potential to improve the qualities of fish meat in food industry. PRACTICAL APPLICATIONS: Compared with other meat, fish meat is particularly easy to break and deteriorate during its processing and sales due to the short length and low cross-linking degree of fish myofibrillar protein, which shows some negative impacts on the quality of fish meat. In the present study, epigallocatechin gallate (EGCG) showed the significant cross-linking effects on carp myofibrillar protein and further improved its physicochemical properties. All results suggested that EGCG had the potential to increase the cross-linking degree of fish myofibrillar protein and improve its properties, so as to ameliorate the quality of fish meat during processing and storage.

Dietary inosine monophosphate improved liver health and flesh quality of gibel carp (Carassius auratus gibelio) via activating AMPK signalling pathway and enhancing the contents of muscle fat and flavour substance

Inosine monophosphate (IMP) improves the flesh quality of livestock and poultry, but studies about its effect on fishes are limited. The aim of the present study was to investigate the effect of exogenous IMP on the liver health and flesh quality of gibel carp (Carassius auratus gibelio). The results showed that IMP supplementation alleviated hepatic lipid deposition by increasing the AMP/ATP ratio and activating the AMPK signaling pathway then decreased inflammatory cytokine expression levels. Additionally, IMP increased the intramuscular fat content. Metabolomic analysis of meat revealed that the IMP, adenosine monophosphate (AMP), guanosine, inosine and purine metabolism pathways were involved in the improvements in fish meat quality, composition and taste that resulted from IMP supplementation. Our study provides a relatively comprehensive assessment of the effect of exogenous IMP on the liver metabolism and flesh quality of farmed fish. The results provide an effective food supplementation strategy for cultured fish.

Effects of dietary protein and lipid levels on growth, feed utilization and meat quality of clown knifefish (Chitala chitala)

Effects of dietary protein and lipid levels on growth, feed utilization and fillet quality of clown knifefish (Chitala chitala) were implemented to determine the protein and energy requirements of this species at 400 g stage. A 4 x 3 factorial design with four dietary protein levels (25%, 30%, 35% and 40%) and three dietary lipid levels (6, 9, and 12%) corresponded to 3 energies levels 18, 19 and 20 MJ/kg. Clown knifefish (407 ± 5.0 g) was stocked at a density of 10 fish/m2. The experiment was arranged in a completely randomized design in triplicate tanks for 8 weeks. There was a significant interaction effect (P<0.05) between protein and lipid levels on weight gain and specific growth rate with the fish growth being highest in the 35 CP-9% lipid treatment. The survival rate of fish was not affected (P>0.05) by dietary protein and lipid levels and ranged from 93.3 to 100%. The feed efficiency of fish was influenced by dietary protein or lipid content as well as the interaction between these two factors. Protein utilization efficiency increased as protein content increased, and diet contained t 35% protein and 9% lipid, enhanced chewiness and hardness of fish paste. These results showed that clown knifefish fed 32.8% dietary protein and 19 MJ energy with a P/E ratio of 18.6 had the optimal growth and the best quality of fish meat.

Comparative analysis of muscle nutrient in two types of hybrid bream and native bream

Distant hybridization can integrate parental advantages to produce new varieties, which may also improve the fish meat quality. Fish is considered to be one of the healthiest meats because it can provide rich protein sources and high levels of omega-3 long-chain polyunsaturated fatty acids. Two types of hybrid bream (BBTB and BTBB) were obtained by the two rounds of backcrossing with an established hybrid lineage of blunt snout bream (Megalobrama amblycephala, BSB, ♀) ​× ​topmouth culter (Culter alburnus, TC, ♂). In the present study, the muscle nutrients, including moisture, fat, protein and ash contents, as well as amino acid and fatty acid compositions, in BBTB, BTBB and their parent BSB with the age of four months were investigated and analyzed by biochemical methods. The results showed that the moisture content of BTBB (76.6%) was lower than that of BSB (77.4%) and BBTB (77.3%), while the protein content of BBTB (17.1%) and BTBB (17.6%) was higher than that of BSB (16.3%). Seventeen amino acids were detected in the muscles from three kinds of fish, among which total amino acids, essential amino acids and delicious amino acids in BTBB and BBTB were all to different degrees higher than those of BSB. Further analysis of fatty acids revealed that BTBB and BBTB exhibited higher levels of unsaturated fatty acids (UFAs) content and the sum content of eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3) in muscle than BSB. Taken together, the results showed the advantages of BBTB and BTBB in nutritional value and taste, which provided theoretical support for their production application.